"Oh my God, no! Oh my God, no!" shouted a woman as she sobbed at the scene. She told police she's the mother of the victim's three children, ages 14, 8, and 2, though they hadn't been in contact recently.

The woman refused to speak with reporters.

The 37-year-old victim was shot and killed on W. 33rd St. by Neptune Ave. (Ken Murray/NEW YORK DAILY NEWS)

Police cordoned a small walkway leading to one of the buildings, where the man's body lay face-down on the ground, beneath a blood-stained sheet.

He had been shot in the head, an NYPD spokesman said.

Early on, cops were looking for three men who fled from the scene, police sources said.